Thank you for the informative session on Therapeutic and Diagnostic Ultrasound. I use this modality in practice, and was interested in viewing the video for interest sake. One comment I have heard from human physiotherapists (from discussions and my CCRT training) is you may need to increase the W/Cm2 or time when doing an underwater application. Evidence (human lit) suggests that ultrasound gel is a better coupling medium than water, and the tissue temperature with an underwater T U/S treatment is not raised as much as with use of coupling gel. A similar case is likely in animals:
http://www.jospt.org/doi/pdf/10.2519/jospt.1993.17.5.247?code=jospt-siteCheers!